Tagged Questions
4
votes
2answers
139 views
Graphene +1 extra carbon bond
I'm not a physicist just a curious mind, so please go easy!
I was just watching a BBC Horizon Documentary that featured a piece on the recently discovered material Graphene. One of the facts ...
0
votes
0answers
96 views
Wave function ansatz for disclinated graphene with spin
I am currently investigating spin dynamics in disclinated graphene. More information about my approach can be found in my other post. I would like to know if my approach is somewhat correct to find ...
3
votes
1answer
109 views
Graphene with a disclination and the spin-orbit coupling
I am trying to follow the methods used in this paper (http://arxiv.org/pdf/1208.3023.pdf) to construct the Hamiltonian of a graphene cone, but taking into account the spin-orbit coupling.
The paper ...
3
votes
2answers
186 views
What limits the maximum attainable Fermi Energy for a material experimentally?
Either through doping or gating. What are some good terms to search for if I'm looking for some experimentally obtained values for particular materials? I'm particularly interested in what the limit ...
2
votes
1answer
126 views
What are the statuses of Silicene and Graphene for real world circuit production?
A lot of hype is out there about both of them (especially the latter) and I was wondering if there is more concrete information about them other than the news IBM posted on a circuit 2 years ago and ...
2
votes
2answers
330 views
Exact diagonalization of graphene's tight binding Hamiltonian
While directly diagonalize graphene's tight binding Hamiltonian, which is numerical. We have to use a finite-sized graphene.
So how to deal with boundary conditions? The usual solutions are zigzag or ...
1
vote
1answer
480 views
Effective Mass and Fermi Velocity of Electrons in Graphene:
In graphene, we have (in the low energy limit) the linear energy-momentum dispersion relation: $E=\hbar v_{\rm{F}}|k|$. This expression arises from a tight-binding model, in fact $E =\frac{3\hbar ...
1
vote
2answers
185 views
Thomas-Fermi approximation and the dielectric function (+ small bit on graphene)
1) With the dielectric function, which is a function of wavenumber and frequency,how is it possible to take the limit of either to zero without changing the other one? I thought that frequency and ...
0
votes
1answer
140 views
Why is the spinor wave function of graphene what it is?
Why is the spinor wave function of graphene $[e^{-i\theta/2}, e^{i\theta/2}]$? Could it be $[e^{-i\theta/}, 1]$?
2
votes
0answers
247 views
Helicity and Pseudospin in Graphene
The Hamiltonian for graphene at $\vec{k}$ away from the $K$ point is proportional to
$$
\vec{\sigma} \cdot \vec{k} =\begin{pmatrix}
0 & k_x - i k_y \\
k_x + i k_y & 0 \\
\end{pmatrix}
=
k ...
4
votes
0answers
155 views
Significance of Dirac cones in condensed matter physics
In condensed matter physics, Dirac cones can be found in graphene, topological insulators, cuprates, and iron-pnictides. This means that electrons behave as massless particles near the Dirac points.
...
5
votes
1answer
270 views
Graphene Moebius Strip
I'm refering to the Paper:
PHYSICAL REVIEW B 80, 195310 (2009)
"MoĢbius graphene strip as a topological insulator"
Z. L. Guo, Z. R. Gong, H. Dong, and C. P. Sun.
The paper is also available as a ...
4
votes
1answer
509 views
Tight Binding Model in Graphene
I'm following a calculation done by a guy who's done it a bit different than what I've done before (used nearest neighbour vectors and a DFT instead of what I will show below), I'm not quite sure how ...
2
votes
0answers
308 views
A question about Dirac operator
The Dirac operator at 2 dimension can be written as
$$
D=\sum_{k=1,2}\sigma^{k}D_{k}=\left( \begin{array}{cc}
0 & \partial_{x}-i\partial_{y}-i(A_x-iA_y)\\
...
3
votes
2answers
435 views
effective theory of graphene
This is a question about deriving effective mass theory for graphene. For the two sub-lattice atoms, the wave equation can be written as the massless Dirac equation:
$ \displaystyle -i\hbar v_F ...
3
votes
1answer
279 views
What is the boundary condition of graphene flake with zigzag edges?
It is a question about free carrier behavior in graphene flakes. (or may be called charge confinement)
Say if we have a perfect hexagonal free standing graphene flake terminated with zigzag edges. ...
8
votes
2answers
1k views
How do Dirac fermions arise in graphene, and, what significance (if any) does this have for high-energy physics?
Graphene has a honeycomb lattice (in the absence of defects and impurities). By considering the low-energy limit of the half-filled Hubbard model used to model the strongly interacting electron gas we ...
